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/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2010 Red Hat, Inc. All rights reserved.
*
* This file is part of LVM2.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU Lesser General Public License v.2.1.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "list.h"
#include <assert.h>
#include <stdlib.h>
/*
* Initialise a list before use.
* The list head's next and previous pointers point back to itself.
*/
void dm_list_init(struct dm_list *head)
{
head->n = head->p = head;
}
/*
* Insert an element before 'head'.
* If 'head' is the list head, this adds an element to the end of the list.
*/
void dm_list_add(struct dm_list *head, struct dm_list *elem)
{
assert(head->n);
elem->n = head;
elem->p = head->p;
head->p->n = elem;
head->p = elem;
}
/*
* Insert an element after 'head'.
* If 'head' is the list head, this adds an element to the front of the list.
*/
void dm_list_add_h(struct dm_list *head, struct dm_list *elem)
{
assert(head->n);
elem->n = head->n;
elem->p = head;
head->n->p = elem;
head->n = elem;
}
/*
* Delete an element from its list.
* Note that this doesn't change the element itself - it may still be safe
* to follow its pointers.
*/
void dm_list_del(struct dm_list *elem)
{
elem->n->p = elem->p;
elem->p->n = elem->n;
}
/*
* Remove an element from existing list and insert before 'head'.
*/
void dm_list_move(struct dm_list *head, struct dm_list *elem)
{
dm_list_del(elem);
dm_list_add(head, elem);
}
/*
* Is the list empty?
*/
int dm_list_empty(const struct dm_list *head)
{
return head->n == head;
}
/*
* Is this the first element of the list?
*/
int dm_list_start(const struct dm_list *head, const struct dm_list *elem)
{
return elem->p == head;
}
/*
* Is this the last element of the list?
*/
int dm_list_end(const struct dm_list *head, const struct dm_list *elem)
{
return elem->n == head;
}
/*
* Return first element of the list or NULL if empty
*/
struct dm_list *dm_list_first(const struct dm_list *head)
{
return (dm_list_empty(head) ? NULL : head->n);
}
/*
* Return last element of the list or NULL if empty
*/
struct dm_list *dm_list_last(const struct dm_list *head)
{
return (dm_list_empty(head) ? NULL : head->p);
}
/*
* Return the previous element of the list, or NULL if we've reached the start.
*/
struct dm_list *dm_list_prev(const struct dm_list *head, const struct dm_list *elem)
{
return (dm_list_start(head, elem) ? NULL : elem->p);
}
/*
* Return the next element of the list, or NULL if we've reached the end.
*/
struct dm_list *dm_list_next(const struct dm_list *head, const struct dm_list *elem)
{
return (dm_list_end(head, elem) ? NULL : elem->n);
}
/*
* Return the number of elements in a list by walking it.
*/
unsigned int dm_list_size(const struct dm_list *head)
{
unsigned int s = 0;
const struct dm_list *v;
dm_list_iterate(v, head)
s++;
return s;
}
/*
* Join two lists together.
* This moves all the elements of the list 'head1' to the end of the list
* 'head', leaving 'head1' empty.
*/
void dm_list_splice(struct dm_list *head, struct dm_list *head1)
{
assert(head->n);
assert(head1->n);
if (dm_list_empty(head1))
return;
head1->p->n = head;
head1->n->p = head->p;
head->p->n = head1->n;
head->p = head1->p;
dm_list_init(head1);
}
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